It came. Very first impressions-
Someone needs to make the instruction text larger. It was more legible than some, but still minimal and of a point size suitable for the vision of birds of prey. The online manual can at least be enlarged, but you need to do tricks to print it in a larger type size.
The device it self seems very well made, and is small, a bit larger than a deck of cards. Operation is straightforward. I’ve only tried it with two headphones so far - it drives the Grados easily, and does a respectable job with the Hifiman HE-560s, powering them to a loud but not thundering volume as you enter the red zone on the volume control.
I have not tried the wireless connectivity yet. I can see that it would be a convenience forte. Given the onboard battery, I used it with the iPhone 6+ and the older, smaller Camera Card 2, rather than the 3. No problems at all. The iPhone volume control is disabled, and the volume control on the xDSD works well. I ran Tidal streaming and Tidal through Roon. Sound is at least the equal of the Dragonfly Black with Jitterbug. I have not tried putting the Jitterbug into the train to see if there is any audible difference.
This is very preliminary. I hope to get to know this beast over the weekend.